Break up SkLazyPixelRef functionally into class hierarchy.

include/core/SkImage.h

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkImage_DEFINED
 #define SkImage_DEFINED
 
@@ skipping 29 matching lines @@
     kLastEnum_SkColorType = kBGRA_8888_SkColorType
 };
 
 struct SkImageInfo {
     int         fWidth;
     int         fHeight;
     SkColorType fColorType;
     SkAlphaType fAlphaType;
 };
 
+bool operator==(const SkImageInfo& lhs, const SkImageInfo& rhs);
+bool operator!=(const SkImageInfo& lhs, const SkImageInfo& rhs);
+
 /**
  *  SkImage is an abstraction for drawing a rectagle of pixels, though the
  *  particular type of image could be actually storing its data on the GPU, or
  *  as drawing commands (picture or PDF or otherwise), ready to be played back
  *  into another canvas.
  *
  *  The content of SkImage is always immutable, though the actual storage may
  *  change, if for example that image can be re-created via encoded data or
  *  other means.
  */
@@ skipping 83 matching lines @@
     const int       fWidth;
     const int       fHeight;
     const uint32_t  fUniqueID;
 
     static uint32_t NextUniqueID();
 
     typedef SkRefCnt INHERITED;
 };
 
 #endif